1. Field of the Invention
The present invention relates to an internal combustion engine having an engine controller and an electronically controlled throttle including a throttle control motor driven by a throttle control circuit.
2. Background Art
An internal combustion engine includes a plurality of cylinders. Each cylinder has an intake and an exhaust and corresponding intake and exhaust valves. A piston is received in each cylinder, and in a spark ignition type engine, a spark plug is also present at each cylinder. In the combustion chamber of a cylinder, a mixture of air and fuel is detonated to drive the engine. The fuel is received in any of a number of known manners such as via injection into the incoming air stream through the intake.
Air flow through the intake manifold is controlled by a throttle including a throttle plate and a throttle actuator. A throttle position sensor senses a position of the throttle.
An engine controller controls various aspects of the engine including injection and spark timing. The controller also electronically controls the throttle plate by providing a signal to the throttle actuator. Typically, the controller provides the signals to the throttle actuator and receives a signal from the throttle position sensor to allow closed loop control of the throttle. The throttle position command sent to the throttle actuator from the controller is determined from, among other things, information received from a driver interface such as fueling demand.
Conventional electronically controlled throttle systems and associated methods have been used in many applications that are commercially successful. However, in certain situations, it may be possible that the throttle actuator, which typically includes a throttle control motor and throttle motor circuit, momentarily does not respond. That is, a momentary open circuit could occur somewhere in the throttle motor circuit causing the throttle to go to a default position because it is unpowered. In such a situation, an existing electronically controlled throttle could respond very quickly when the momentary motor open circuit lapses and the circuit is then again closed. The quick response of the electronically controlled throttle after the momentary motor open circuit may be undesirable in certain situations. For the foregoing reasons, there is a need for a method of controlling an internal combustion engine having an electronically controlled throttle wherein throttle control after a momentary open circuit is precisely controlled so as to reduce the possibility for undesirable abrupt throttle plate position changes.
It is, therefore, an object of the present invention to provide a method of controlling an internal combustion engine having an electronically controlled throttle wherein after detection of a closed circuit condition following a momentary open circuit condition, the throttle position command is clipped and then applied to the throttle control motor, providing a smooth response to increased throttle demand after the momentary open circuit.
In carrying out the above object, a method of controlling an internal combustion engine is provided. The engine has an engine controller and an electronically controlled throttle including a throttle control motor driven by a throttle control circuit. The method comprises determining a throttle position command for the throttle control motor, and applying the throttle position command to the throttle control motor with the throttle control circuit. The method further comprises detecting an open circuit condition in the throttle control circuit, detecting a closed circuit condition in the throttle control circuit, and after detection of the closed circuit condition, clipping the throttle position command. The clipped throttle position command is applied to the throttle control motor with the throttle control circuit.
In a preferred embodiment, the electronically controlled throttle further includes a throttle position sensor. Detecting the open circuit condition further comprises determining an actual throttle position with the throttle position sensor, and comparing the throttle position command to the actual throttle position. The open circuit condition is detected based on the comparison. Further, in a preferred embodiment, the throttle has a nominal default position, an open stop position, and a close stop position. Detecting the open circuit condition based on the comparison further comprises determining a held against stop mode for the throttle based on the comparison. When the held against stop mode is present, the actual throttle position is stored as the open position when the present held against stop mode is a held against open stop mode. When the present held against stop mode is a held against close stop mode, the actual throttle position is stored as the close stop position. And, when the held against stop mode is present, the open circuit condition is detected when the actual throttle position is near the nominal default position and the actual throttle position is inappropriate for the present held against stop mode. Even further, in a preferred embodiment, detecting the closed circuit condition further comprises detecting the closed circuit condition when the actual throttle position is no longer near the nominal default position.
Further, in carrying out the invention, a system for controlling an internal combustion engine is provided. The system includes an engine controller and an electronically controlled throttle including a throttle control motor driven by a throttle control circuit. The system is configured to determine a throttle position command for the throttle control motor, and apply the throttle position command to the throttle control motor with the throttle control circuit. The system is further configured to detect an open circuit condition in the throttle control circuit, detect a closed circuit condition in the throttle control circuit, and after detection of the closed circuit condition, clip the throttle position command. The clipped throttle position command is applied to the throttle control motor with the throttle control circuit. In a preferred embodiment, other aspects of the preferred method may be incorporated.
Further, in carrying out the present invention, an internal combustion engine is provided. The engine has an engine controller and an electronically controlled throttle including a throttle control motor driven by a throttle control circuit. The engine is configured to determine a throttle position command for the throttle control motor, and apply the throttle position command to the throttle control motor with the throttle control circuit. The engine is further configured to detect an open circuit condition in the throttle control circuit, detect a closed circuit condition in the throttle control circuit, and after detection of the closed circuit condition, clip the throttle position command. The clipped throttle position command is applied to the throttle control motor with the throttle control circuit. In a preferred engine, other aspects of the preferred method may be incorporated.
The advantages associated with embodiments of the present invention are numerous. For example, should a momentary open circuit occur somewhere in the throttle motor circuit, the following scenario could take place. Throttle command is 20xc2x0. The motor open circuit occurs. Throttle goes to default (for example, 5xc2x0 ) because it is unpowered. The driver notices the reduced power, and steps into the accelerator petal. Throttle command goes to 80xc2x0. Low engine power continues. Then, the motor circuit closes. In a conventional electronically controlled throttle, a driver could be surprised by a quick power increase. In accordance with the present invention, the open circuit is detected, the subsequent closing of the circuit is detected, and the throttle position command is limited or clipped prior to application to the throttle control motor, resulting in smooth changing of the applied throttle position command.
The above object and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the preferred embodiment when taken in connection with the accompanying drawings.